Field of the Invention
The invention relates to a signal processing device, etc., capable of filtering measuring data received from a measuring device and transferring the same to a control device.
Description of Related Art
A known signal processing device is adapted to acquire a physical quantity measured by a sensor installed in industrial machinery such as a measuring device, etc., and perform signal processing to the acquired detection signal, and transfer the signal to a control device used for controlling the industrial machinery. The signal processing device may amplify an analog signal acquired from the sensor, and convert the analog signal into a digital signal by using an analog-to-digital (AD) converter, and transfer the digital signal to the control device. Moreover, the signal processing device uses a digital filter to filter a noise in the digital signal, and sends the filtered digital signal to the control device.
In a control system including the signal processing device, measuring objects (generally referred to as works) measured by a measuring device are diversified, and the noises generated corresponding to the measuring objects are also different. Therefore, the noises to be eliminated by the signal processing device are not necessarily the same, and each time a frequency of the noise to be eliminated has to be set corresponding to the measuring object.
Moreover, a patent literature 1 discloses a following technique: in a measuring device, a motor speed signal is taken as a base frequency, and amplitude of a specified frequency obtained by multiplying the base frequency by a multiplying power is used to determine an abnormal state. According to such technique, the motor speed signal can be used to determine the abnormal state, such that even the measuring object is changed, the abnormal state can still be easily determined.